1. Field of the Invention
The present invention relates generally to the treatment of anatomical tissue of the head and/or neck with high intensity focused ultrasound energy and, more particularly, to tonsil reduction by thermal ablation using high intensity focused ultrasound.
2. Brief Description of the Related Art
When high intensity ultrasound energy is applied to anatomical tissue, significant physiological effects may be produced in the anatomical tissue resulting from thermal and/or mechanical changes or effects in the tissue. Thermal effects include heating of the anatomical tissue; and, when the tissue is heated to a sufficiently high temperature, tissue damage such as coagulative necrosis is produced. In order to produce thermal effects in anatomical tissue, ultrasound emitting members such as transducers have been used to emit ultrasound energy which is applied to anatomical tissue by positioning the ultrasound emitting members adjacent or in contact with the tissue or by coupling the ultrasound emitting members to the tissue via an acoustic coupling medium. By focusing the ultrasound energy at one or more specific focusing zones within the tissue, thermal effects can be confined to a defined location, region, volume or area, and such location, region, volume or area can be remote from the ultrasound emitting member.
With the use of high intensity focused ultrasound (HIFU), one or more focusing zones at or within a designated target location, region, volume or area within a larger mass, body or area of anatomical tissue can be subjected to high intensity ultrasound energy while tissue surrounding the target area is subjected to much lower intensity ultrasound energy. In this manner, tissue in the target area can be heated to a sufficiently high temperature so as to cause a desired thermal effect such as tissue damage, ablation, coagulation, denaturation, destruction or necrosis while tissue surrounding the target area is not heated to damaging temperatures and, therefore, is preserved. Heating of tissue in a target location, volume, region or area to an ablative temperature creates an ablative lesion in the tissue in the target location, volume, region or area that is desirable in the treatment of various medical conditions, disorders or diseases. For example, the lesion may remain as tissue having altered characteristics or may be naturally degraded and absorbed by the patient""s body and thusly eliminated such that the remaining body, mass or area of tissue is of smaller volume or size due to the absence of the ablated tissue.
The use of high intensity focused ultrasound to eliminate tissue or to alter the characteristics of tissue in a target location, volume, region or area within a larger mass, body or area of anatomical tissue presents many advantages including minimization of trauma and pain for the patient, elimination of the need for a surgical incision, stitches and exposure of internal tissue, avoidance of damage to tissue other than that which is to be treated, altered or removed, lack of a harmful cumulative effect from the ultrasound energy on the surrounding non-target tissue, reduction in treatment costs, elimination of the need in many cases for general anesthesia, reduction of the risk of infection and other complications, avoidance of blood loss, and the ability for high intensity focused ultrasound procedures to be performed in non-hospital sites and/or on an out-patient basis.
Various devices and/or methods for treating anatomical tissue with ultrasound have been proposed as represented by U.S. Pat. No. Re. 33,590 to Dory, U.S. Pat. No. 3,990,452 to Murry et al, U.S. Pat. No. 4,658,828 to Dory, U.S. Pat. No. 4,807,633 to Fry, U.S. Pat. No. 4,858,613 to Fry et al, U.S. Pat. No. 4,951,653 to Fry et al, U.S. Pat. No. 4,955,365 to Fry et al, U.S. Pat. No. 5,033,456 to Pell et al, U.S. Pat. No. 5,036,855 to Fry et al, U.S. Pat. No. 5,054,470 to Fry et al, U.S. Pat. No. 5,065,761 to Pell, U.S. Pat. No. 5,080,101 to Dory, U.S. Pat. No. 5,080,102 to Dory, U.S. Pat. No. 5,117,832 to Sanghvi et al, U.S. Pat. No. 5,134,988 to Pell et al, U.S. Pat. No. 5,143,074 to Dory, U.S. Pat. No. 5,150,711 to Dory, U.S. Pat. No. 5,150,712 to Dory, U.S. Pat. No. 5,158,070 to Dory, U.S. Pat. No. 5,222,501 to Ideker et al, U.S. Pat. No. 5,267,954 to Nita, U.S. Pat. No. 5,269,291 to Carter, U.S. Pat. No. 5,269,297 to Weng et al, U.S. Pat. No. 5,295,484 to Marcus et al, U.S. Pat. No. 5,304,115 to Pflueger et al, No. 5,312,328 to Nita et al, U.S. Pat. No. 5,318,014 to Carter, U.S. Pat. No. 5,342,292 to Nita et al, U.S. Pat. No. 5,354,258 to Dory, U.S. Pat. No. 5,380,274 to Nita, U.S. Pat. No. 5,391,197 to Burdette et al, U.S. Pat. No. 5,397,301 to Pflueger et al, U.S. Pat. No. 5,409,002 to Pell, U.S. Pat. No. 5,417,672 to Nita et al, U.S. Pat. No. 5,431,621 to Dory, No. 5,431,663 to Carter, U.S. Pat. No. 5,447,509 to Mills et al, U.S. Pat. No. 5,474,530 to Passafaro et al, U.S. Pat. No. 5,492,126 to Hennige et al, U.S. Pat. No. 5,501,655 to Rolt et al, U.S. Pat. No. 5,520,188 to Hennige et al, U.S. Pat. No. 5,542,917 to Nita et al, U.S. Pat. No. 5,620,479 to Diederich, U.S. Pat. No. 5,676,692 to Sanghvi et al, U.S. Pat. No. 5,728,094 to Edwards, U.S. Pat. No. 5,730,719 to Edwards, U.S. Pat. No. 5,733,315 to Burdette et al, U.S. Pat. No. 5,735,280 to Sherman et al, U.S. Pat. No. 5,738,114 to Edwards, U.S. Pat. No. 5,746,224 to Edwards, U.S. Pat. No. 5,762,066 to Law et al, U.S. Pat. No. 5,800,379 to Edwards, U.S. Pat. No. 5,800,429 to Edwards, U.S. Pat. No. 5,800,482 to Pomeranz et al, U.S. Pat. No. 5,807,308 to Edwards, U.S. Pat. No. 5,817,049 to Edwards, U.S. Pat. No. 5,823,197 to Edwards, U.S. Pat. No. 5,827,277 to Edwards, U.S. Pat. No. 5,843,077 to Edwards, U.S. Pat. No. 5,871, 524 to Knowlton, U.S. Pat. No. 5,873,845 to Cline et al, U.S. Pat. No. 5,873,902 to Sanghvi et al, U.S. Pat. No. 5,879,349 to Edwards, U.S. Pat. No. 5,882,302 to Driscoll, Jr. et al, U.S. Pat. No. 5,895,356 to Andrus et al, No. 5,928,169 to Schatzle et al and U.S. Pat. No. 5,938,608 to Bieger et al.
In particular, the use of high intensity focused ultrasound to thermally damage, ablate, coagulate, denature, cauterize, necrotize or destroy a target volume of tissue is exemplified by U.S. Pat. No. Re. 33,590 to Dory, U.S. Pat. No. 4,658,828 to Dory, U.S. Pat. No. 4,807,633 to Fry, U.S. Pat. No. 4,858,613 to Fry et al, U.S. Pat. No. 4,951,653 to Fry et al, U.S. Pat. No. 4,955,365 to Fry et al, U.S. Pat. No. 5,036,855 to Fry et al, U.S. Pat. No. 5,054,470 to Fry et al, U.S. Pat. No. 5,080,101 to Dory, U.S. Pat. No. 5,080,102 to Dory, U.S. Pat. No. 5,117,832 to Sanghvi et al, U.S. Pat. No. 5,143,074 to Dory, U.S. Pat. No. 5,150,711 to Dory, U.S. Pat. No. 5,150,712 to Dory, U.S. Pat. No. 5,295,484 to Marcus et al, U.S. Pat. No. 5,354,258 to Dory, U.S. Pat. No. 5,391,197 to Burdette et al, U.S. Pat. No. 5,431,621 to Dory, U.S. Pat. No. 5,492,126 to Hennige et al, U.S. Pat. No. 5,501,655 to Rolt et al, U.S. Pat. No. 5,520,188 to Hennige et al, U.S. Pat. No. 5,676,692 to Sanghvi et al, U.S. Pat. No. 5,733,315 to Burdette et al, U.S. Pat. No. 5,762,066 to Law et al, U.S. Pat. No. 5,871,524 to Knowlton, U.S. Pat. No. 5,873,845 to Cline et al, U.S. Pat. No. 5,873,902 to Sanghvi et al, U.S. Pat. No. 5,882,302 to Driscoll, Jr. et al, U.S. Pat. No. 5,895,356 to Andrus et al, U.S. Pat. No. 5,928,169 to Schatzle et al and U.S. Pat. No. 5,938,608 to Bieger et al.
Ablation of anatomical tissue of the head and/or neck in order to treat various airway related disorders or conditions, such as airway obstructions, snoring disorders and sleep apnea syndrome, has been proposed as illustrated by U.S. patents U.S. Pat. No. 5,423,812 to ElIman et al, U.S. Pat. Nos. 5,456,662, 5,514,131, 5,624,439, 5,674,191, 5,707,349, 5,718,702, 5,728,094, 5,730,719, 5,738,114, 5,743,870, 5,743,904, 5,746,224, 5,800,379, 5,800,429, 5,807,308, 5,817,049, 5,823,197, 5,827,277, 5,843,077 and 5,879,349 to Edwards and WO 97/43970. The latter patents disclose ablation of various structures of the anatomical airway to alleviate or eliminate snoring disorders and/or obstructive sleep apnea syndrome in patients. U.S. Pat. No. 5,423,812 relates to electrosurgical stripping of tissue. U.S. Pat. Nos. 5,456,662, 5,514,131, 5,624,439, 5,674,191, 5,707,349, 5,718,702, 5,728,094, 5,730,719, 5,738,114, 5,743,870, 5,743,904, 5,746,224, 5,800,379, 5,800,429, 5,807,308, 5,817,049, 5,823,197, 5,827,277, 5,843,077, 5,879,349 and WO 97/43970 disclose RF ablation using tissue penetrating electrodes. U.S. Pat. Nos. 5,707,349, 5,728,094, 5,730,719, 5,738,114, 5,746,224, 5,800,379, 5,800,429, 5,807,308, 5,817,049, 5,823,197, 5,827,277, 5,843,077 and 5,879,349 refer to ultrasound as a possible source of ablative energy.
Sleep apnea syndrome is a medical condition characterized by episodes of apnea during sleep causing daytime hypersomnomulence, morning arm aches, intellectual deterioration, cardiac arrhythmias, snoring and/or thrashing during sleep. Snoring disorders are chiefly caused by vibration of tissue or anatomical structures of the airway and/or blockage, obstruction, occlusion or restriction of the airway by tissue or structures thereof.
Treatments for snoring disorders and/or sleep apnea syndrome have included various pharmacological, surgical and physical measures to reduce or eliminate tissue vibrations and/or airway obstructions or restrictions so as to enhance the flow of air through the patient""s airway. Pharmacological measures have included the use of medications such as protriptolene, medroxyprogesterone, acetasolemide, theophylline, nicotine and other medications in addition to avoidance of central nervous system depressants such as sedatives or alcohol. Such medications typically have undesirable side effects and are of limited effectiveness. Surgical measures have included uvulopalatal pharyngoplasty, tonsillectomy, surgery to correct severe retrognathia and tracheostomy. Other surgical measures have included removing a portion or portions of anatomical tissue or structures which can obstruct or restrict the patient""s airway.
Surgical techniques have been proposed using standard surgical instruments, laser energy and RF energy. Although surgical measures are generally more effective than medications, the risks associated with surgery can be prohibitive and/or are often unacceptable to the patient. In addition, conventional surgery is associated with considerable trauma and pain for the patient as well as the potential for post-operative complications. Laser and RF energy ablation procedures are less invasive than surgery with standard surgical instruments but are difficult to control; and, if too much tissue is ablated, severe consequences may ensue. Multiple ablation treatments are usually required in order to achieve the results desired, and each treatment may cause the patient to experience significant pain for a considerable length of time. Laser and RF energy ablation systems are not able to repeatedly and consistently produce an ablated tissue area of definitive size. Physical measures to treat snoring disorders and/or sleep apnea syndrome include weight loss and the use of various appliances.
The tonsils, due to their size and/or position in relation to other tissues or anatomical structures of the airway, may produce vibrations and/or obstruct or restrict the airway and thusly contribute to snoring disorders and/or obstructive sleep apnea syndrome. The tonsils also may support infections and illnesses since the passageways or interstices of the tonsils can harbor bacteria. Current techniques to remove the tonsils include ablation with laser or RF energy and avulsing the tissue with standard surgical instruments such as snares, scissors or blunt dissecting instruments. Current techniques involve considerable pain and recovery time and may result in undesired blood loss. In addition, the muscular tissue level of the tonsils may be damaged resulting in increased blood loss and postoperative pain.
Electrosurgical stripping of tissue of the tonsils in layers as a treatment for snoring disorders and obstructive sleep apnea is disclosed in U.S. Pat. No. 5,423,812 to Ellman et al. Ablation of the tonsils to treat snoring disorders and/or obstructive sleep apnea syndrome is contemplated by U.S. Pat. Nos. 5,514,131, 5,624,439, 5,707,349, 5,718,702, 5,728,094, 5,730,719, 5,738,114, 5,743,904, 5,800,379, 5,807,308, 5,817,049 and 5,879,349 to Edwards, all of which disclose penetration of tissue by RF electrodes used to transmit electromagnetic energy to ablate the tissue. No teachings are provided by which ablation of the tonsils can be accomplished without penetration of the tonsils by the electrodes. U.S. Pat. Nos. 5,728,094, 5,730,719, 5,738,114, 5,800,379, 5,807,308, 5,817,049 and 5,879,349 merely allude to ultrasound as a possible source of ablative energy.
Accordingly, the need exists for methods of tonsil reduction by thermal ablation using high intensity focused ultrasound whereby one or both tonsils of a patient can be reduced, via elimination and/or alteration of the normal tissue, to thereby alleviate or eliminate vibration of the tonsil, to increase the space or size of the patient""s airway and/or to treat infectious illnesses in a minimally invasive, bloodless procedure not requiring physical penetration of the tonsil by the member used to deliver the ultrasound energy and while confining ablation to a specific target area or areas within the tonsil.
Accordingly, it is a primary object of the present invention to overcome the various disadvantages of prior methods of tonsil reduction and/or removal.
It is also an object of the present invention to effect tonsil reduction by thermal ablation using high intensity focused ultrasound.
Another object of the present invention is to utilize high intensity focused ultrasound to treat airway obstructions.
A further object of the present invention is to utilize high intensity focused ultrasound to treat snoring disorders.
An additional object of the present invention is to utilize high intensity focused ultrasound to treat obstructive sleep apnea syndrome.
It is also an object of the present invention to use high intensity focused ultrasound to create a coagulative tissue area in a tonsil to permit removal of the tonsil with minimal or no blood loss.
Yet another object of the present invention is to use high intensity focused ultrasound to produce an ablated tissue area in a tonsil including unablated tissue and a plurality of lesions at which the tissue is ablated while preserving the mucosa of the tonsil.
The present invention has as a further object to use high intensity focused ultrasound to form a subsurface ablated tissue area in a tonsil including unablated tissue and relatively stiffer, ablated tissue to inhibit tonsular vibration.
The present invention also has as an object to use high intensity focused ultrasound to ablate a tonsil at an internal target area without physical penetration of the tonsil by the member used to deliver the ultrasound energy.
Still a further object of the present invention is to focus ultrasound energy within a tonsil to form an internal ablated tissue area beginning a predetermined distance beneath an external surface of the tonsil and including unablated tissue and a plurality of lesions at which the tissue is ablated.
The present invention also has as an object to focus ultrasound energy, emitted by an ultrasound emitting member, within a tonsil to ablate tissue of the tonsil at a target area beginning a predetermined distance from an active face of the ultrasound emitting member.
It is another object of the present invention to use high intensity focused ultrasound to form an ablated tissue area in a tonsil to a predetermined depth so that muscular tissue external to the tonsil capsule is not damaged.
Additionally, it is an object of the present invention to ablate a tonsil to form an ablated tissue area therein containing coagulatively necrotized tissue and being surgically removable with minimal pain and blood loss.
Some of the advantages of the present invention are that varying intensity levels of ultrasound energy can be delivered to tissue of a tonsil for varying periods of time depending on desired ablative effect, the duration of ultrasound energy delivery or application to the tissue needed to accomplish a desired ablation may be relatively brief depending on desired size for the lesions of the ablated tissue area and/or desired thermal effect on the tissue, the transducer or other member used to emit the ultrasound energy may be stationary or may be movable in order to scan a target area with focused ultrasound, a plurality of individual ablated tissue areas can be formed in a tonsil with the ablated tissue areas being separate and discontinuous or being contacting, abutting, contiguous or overlapping to form a single continuous ablated tissue area of desired size and/or shape, the ultrasound emitting member can remain stationary or can be moved along a tonsil to scan a target area with focused ultrasound, the transducer or other member may be designed with a focusing configuration designed to ensure that the lesions of the ablated tissue area have a desired cross-sectional size, begin a desired depth within the tissue and have a desired depth, a tonsil may be effectively removed or reduced in size, volume and/or configuration, tissue of a tonsil may be rigidified or stiffened via thermal damage thereto to reduce the volume of relatively softer, normal tonsular tissue, tonsil reduction and/or removal is/are accomplished with minimal trauma and pain for the patient, the transducer or other member is positioned externally adjacent or in contact with an external surface of the tonsil or is acoustically coupled with tissue of the tonsil to form an internal ablated tissue area without damaging the external tissue surface and without formation of fistulas, no external wound is presented where the mucosa of the tonsil is preserved, and an ablated tissue area of definitive size can be repeatedly and consistently produced.
These and other objects, advantages and benefits are realized with the present invention as generally characterized in a method of tonsil reduction by thermal ablation using high intensity focused ultrasound wherein an ultrasound emitting member is introduced in a patient""s oral cavity and is positioned externally adjacent an external tissue surface of a tonsil. Ultrasound energy is emitted from the ultrasound emitting member into the tissue of the tonsil, and the ultrasound energy is focused within the tonsil at a plurality of focusing zones disposed beneath the external tissue surface. The focusing zones are spaced from one another and, due to focusing of the ultrasound energy at the focusing zones, the ultrasound energy is of higher or greater intensity in the tissue at the focusing zones than in the tissue surrounding the focusing zones. The tissue of the tonsil is heated at the focusing zones by the focused ultrasound energy, thereby forming an ablated tissue area containing unablated tonsular tissue and a plurality of lesions at the focusing zones, respectively, at which the tissue of the tonsil is ablated. Where the tonsil is not to be surgically removed as part of the same procedure, the ablated tissue area is preferably formed beneath the external tissue surface. Where the tonsil is to be removed surgically as part of the same procedure, the ablated tissue area may include the external tissue surface. Once an ablated tissue area of desired extent has been obtained in the tonsil, the ultrasound emitting member is withdrawn from the patient""s oral cavity. The ablated tissue area may be surgically removed with minimal pain and blood loss or may be allowed to remain in the patient""s body. Where the ablated tissue area is allowed to remain in the patient""s body, the lesions may be subsequently degraded and absorbed by the patient""s body such that the tonsil is smaller in size than prior to treatment. The lesions may subsequently remain as altered tissue, such as scar tissue that is stiffer, tighter or more rigid than the normal undamaged tonsular tissue, the volume of normal undamaged tonsular tissue therefore being less than prior to treatment. Since the tonsil is removed or is smaller in size and/or more stiff, the patient""s airway is correspondingly larger in size and/or the tonsil is less likely to vibrate so as to eliminate or alleviate various airway related disorders or conditions including airway obstructions, snoring disorders and sleep apnea syndrome. In addition, the tonsil as a source of infection may be eliminated.
The ultrasound emitting member has a focusing configuration causing the ultrasound energy to be focused a predetermined distance from an active face of the ultrasound emitting member and, therefore, from the external tissue surface, so that the mucosa of the tonsil may be preserved. Also, the focusing configuration results in formation of lesions of predetermined or known depth in accordance with the length of the focusing zones, the selected ultrasound energy intensities and the selected duration times for ultrasound energy delivery. The lesion depths are selected so that the lesions do not extend deeper than desired in the tissue. The plurality of lesions may be non-contacting, with each lesion surrounded by unablated tonsular tissue. One or more of the plurality of lesions may contact another one of the plurality of lesions. The cross-sectional size of the lesions and the location and arrangement of the focusing zones in the tissue result in formation of a specific size ablated tissue area having a specific cross-sectional configuration. A single, discrete ablated tissue area or a plurality of single, discrete ablated tissue areas can be formed in the tonsil in a single procedure or treatment performed at one time or in multiple procedures or treatments performed at different times. Where a plurality of ablated tissue areas are formed, the ablated tissue areas can be contiguous, contacting, overlapping or in abutment with one another so that the ablated tissue areas together form or create a single ablated tissue area of larger cross-sectional size and/or of a desired cross-sectional configuration.